cephadm: set auth_allow_insecure_global_id_reclaim for mon on bootstrap

cephadm: set auth_allow_insecure_global_id_reclaim for mon on bootstrap

If this is a fresh pacific cluster, let's assume that there won't be
legacy clients connecting.  (And if there are, let's put the burden on
the user to enable them to do so insecurely.)

This is in contrast to upgrades, where our focus is on not breaking
anything.

Signed-off-by: Sage Weil <sage@newdream.net>
(cherry picked from commit 7ca74183226b1125b29f4ea8f324ae9e38b46795)

Conflicts:
	src/cephadm/cephadm [ commit 369989ebf90c ("cephadm: split-off
	  config work on bootstrap") not in octopus ]